SALEM — A man who was injured in an explosion last summer that killed his girlfriend, her son and granddaughter as well as three others is now receiving death threats as speculation swirls about the cause of the tragedy.

State Police have not named Steven McComsey or anyone else as a suspect in the house explosion that left six people dead July 13. But speculation surrounding the explosion's cause has picked up recently following changes on the death certificates for at least four victims that now state the manner of death as "homicide" where it was once listed as "accidental."

McComsey didn't suffer the extensive physical injuries others did, but he can't sleep and he has received death threats, said his lawyer, Paul Wein. He is worried because of what people are saying now, that without answers, they will conclude he did something wrong, Wein said.

The State Police are investigating the explosion, but referred questions to Washington County District Attorney Kevin Kortright, who confirmed the changes to the death certificates but would not comment further. He said he has been meeting with State Police every few months to discuss the case but has no meeting coming up.

Three lawyers who represent victims of the explosion said they are baffled by the changes.

"It's crazy. It makes no sense," said Wein, McComsey's attorney. "What could have caused them to do it unless they have proof?"

The baby's mother, Alicia Berg, also Palmer's daughter, survived but suffered a traumatic brain injury. The other survivors were Brianna Berg and Dan and Chelsey Wilcox, a father and daughter who were visiting that day.

The family had been complaining about a bad smell in the house before the explosion and according to Kevin Luibrand, a lawyer for Dan and Chelsey Wilcox, McComsey asked Dan Wilcox to help him find the source of the smell in the basement just minutes before the explosion.

In August, police said a spark in a water system ignited a cloud of propane, but did not say what caused the propane to accumulate inside the home.

Wein said the incident seems like a case of simple negligence. There were two propane tanks on the property. One provided fuel for appliances the tenants used every day. The other tank had once been connected to appliances inside a separate apartment in the building, but was disconnected and no longer in use. According to police, 26 gallons of propane were put into the unused tank in January 2010 and the tank was last used in March 2010. It had 24 gallons of propane inside it after the explosion, police said.

Wein said the pipes from the unused tank weren't properly tied off and it could have led to the explosion.

"I'm not a police investigator, but that is what I would be looking at," Wein said.

An attorney for the company that filled the tanks disagrees. "Suburban Propane denies any wrongdoing and we await the results of the State Police investigation," said Jim Hacker, an attorney for the propane company.

McComsey had no motive to blow up the house, Wein said.

"If he did something to trigger the explosion he would have been long gone," Wein said. "But he was there, he was looking at the bodies of his family."

Luibrand said Dan Wilcox's statement to police corroborates what McComsey has had to say.

"If Steven McComsey is a suspect, it seems hard to believe. He was in the basement five minutes before the house was incinerated, asking Dan Wilcox to help him identify the smell, then showing him woodwork he'd been doing," Luibrand said.

The two men then started calling for everyone to get out of the house because they were afraid the mysterious odor might be gas, Luibrand said. Niah Durham was already in her infant carrier because her family was preparing to leave the house, Luibrand said.

"Chelsey picked up the car seat off the kitchen table and the next thing she knew, she was thrown 15 feet in the air," Luibrand said.